U.S. patent application number 16/162089 was filed with the patent office on 2019-04-18 for electrical telescopic strut construction.
The applicant listed for this patent is CESA, C. Espanola de Sistemas Aeronauticos, S.A.. Invention is credited to Francisco Jose AGUADO LOPEZ, Jose Luis CRESPO CHICO, Rosa MACIAS CUBEIRO, Esteban MORANTE LOPEZ.
Application Number | 20190113115 16/162089 |
Document ID | / |
Family ID | 60201974 |
Filed Date | 2019-04-18 |
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United States Patent
Application |
20190113115 |
Kind Code |
A1 |
MACIAS CUBEIRO; Rosa ; et
al. |
April 18, 2019 |
ELECTRICAL TELESCOPIC STRUT CONSTRUCTION
Abstract
Electrical telescopic strut construction, movable between an
extended locked position and a retracted unlocked position,
comprising: an external cylinder (1); an inner cylinder (2); a
screw (3) rotatable disposed within the inner cylinder (2); a drive
(4) configured to rotate the screw (3); a nut (5) being movable
with respect to the external cylinder (1) responsive to the
rotation of the screw (3); at least one segment (6) located in a
radial opening of the inner cylinder (2) and movable radially
outward and inward in response to the movement of the nut (5) and
configured to engage the external cylinder (1) when moved radially
outward and not to engage the external cylinder (1) when moved
radially inward, a second inner cylinder (7) located external to
the first inner cylinder (2) and internal to the external cylinder
(1).
Inventors: |
MACIAS CUBEIRO; Rosa;
(Getafe, ES) ; CRESPO CHICO; Jose Luis; (Getafe,
ES) ; MORANTE LOPEZ; Esteban; (Getafe, ES) ;
AGUADO LOPEZ; Francisco Jose; (Getafe, ES) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CESA, C. Espanola de Sistemas Aeronauticos, S.A. |
Getafe |
|
ES |
|
|
Family ID: |
60201974 |
Appl. No.: |
16/162089 |
Filed: |
October 16, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H 2025/2071 20130101;
F16H 2025/2081 20130101; F15B 15/088 20130101; B66F 3/10 20130101;
B64C 13/50 20130101; F16H 25/20 20130101; F15B 15/14 20130101; B64D
29/08 20130101 |
International
Class: |
F16H 25/20 20060101
F16H025/20; F15B 15/08 20060101 F15B015/08; F15B 15/14 20060101
F15B015/14; B64C 13/50 20060101 B64C013/50 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 17, 2017 |
EP |
17382688.4 |
Claims
1. An electrical telescopic strut construction, movable between an
extended locked position and a retracted unlocked position,
comprising: an external cylinder having a connection at an end; an
inner cylinder slidable within the external cylinder and having a
second connection at an end; a screw rotatable disposed within the
inner cylinder; a drive configured to rotate the screw; a nut
coupled to the screw and connected to the inner cylinder, being
movable with respect to the external cylinder responsive to the
rotation of the screw; at least one segment located in a radial
opening of the inner cylinder and movable radially outward and
inward in response to the movement of the nut and configured to
engage the external cylinder when moved radially outward and not to
engage the external cylinder when moved radially inward, the inner
cylinder being lockable to the external cylinder by the segment in
an extended position of the strut, wherein the strut further
comprises a second inner cylinder located external to the first
inner cylinder and internal to the external cylinder when the first
inner cylinder is retracted into the external cylinder, the second
inner cylinder being joined to the first inner cylinder such that
both cylinders are displaceable together and the second inner
cylinder being in axial contact with the first inner cylinder.
2. The electrical telescopic strut construction according to claim
1, further comprising a mechanical element extending radially
between the first inner cylinder and the second inner cylinder
configured to avoid the axial and radial relative movement between
both cylinders.
3. The electrical telescopic strut construction according to claim
2, wherein the mechanical element is a pin located in an opening of
the first inner cylinder and in an opening of the second inner
cylinder.
4. The electrical telescopic strut construction according to claim
1, further comprising a mechanical element extending between the
inner cylinder and the nut configured to avoid the radial relative
movement between both elements.
5. The electrical telescopic strut construction according to claim
4, wherein the mechanical element is a pin located in an opening of
the inner cylinder and in an opening of the nut.
6. The electrical telescopic strut construction according to claim
5, wherein the opening of the nut is an axial opening such that
there is an axial relative movement between the inner cylinder and
the nut.
7. The electrical telescopic strut construction according to claim
1, wherein the second inner cylinder has a pair of connections at
its free end coaxial with the connection of the inner cylinder.
8. The electrical telescopic strut construction according to claim
1, wherein the external cylinder has a pair of connections at its
end coaxial with the connection of the external cylinder that are
configured to be in axial contact with the external cylinder and to
act in case of failure of the first connection.
9. The electrical telescopic strut construction according to claim
1, wherein the nut comprises a collar located around the nut
comprising two surfaces of different external diameter, one leaving
the segment in a lower position and therefore not engaging the
external cylinder and a second cylindrical surface having a larger
diameter and locating the segment engaging the external
cylinder.
10. The electrical telescopic strut construction according to claim
9, wherein the sliding surfaces between segment and collar comprise
both a zero or negative angle.
Description
FIELD OF THE INVENTION
[0001] The present invention refers to an electrical telescopic
strut construction for locking/unlocking aircraft cowls under load.
The strut is movable between an extended, locked position and a
retracted, unlocked position.
[0002] The project leading to this application has received funding
from the European Union's Horizon 2020 research and innovation
programme under grant agreement No 636218.
BACKGROUND OF THE INVENTION
[0003] As aircraft cowlings tend to be hefty, especially those
covering large aircraft engines, and their weight can amount to
hundreds of kilograms, an inadvertent unlocking of the collapsible
strut construction in its extended, locked position results in a
rapid, unpredictable closure of the aircraft cowling that may
result in serious injury or even death of an operator performing
maintenance operations of the engine beneath the aircraft cowling.
Different solutions aimed at preventing an inadvertent unlocking of
the collapsible strut construction in its extended, locked
position.
[0004] A plurality of collapsible strut constructions have been
employed over past years for supporting aircraft cowlings in an
open position as, for example, during maintenance operations of the
engines. Linear collapsible mechanical struts are also employed in
various environments and applications for moving one mechanical
part relative to another mechanical part.
[0005] The struts may be powered by a hydraulic motor drive or by
an electric motor drive. One example application is for aircraft
wherein actuators may be employed to deploy and retract various
assemblies, e.g., a landing gear, a cargo door, a foldable part
such as part of a wing, blade or tall, and other similar parts.
Said actuators must withstand substantial loads and the drive
mechanism must be made substantially stronger so that it can bear
the applied loads. As a result the actuator and its drive mechanism
can be quite heavy.
[0006] One of the disadvantages of known systems is that, due to
the high load the strut must withstand, the elements are damaged
resulting in a malfunctioning or an inadvertent unlocking of the
system.
[0007] Additionally, known struts are not fall safe against the
damage of one of its components. To solve this two independent
actuators are typically used. Some double load paths struts are
also used, usually having two screws, a conventional screw and an
inverted screw. The disadvantages of said systems are that it
increases the weight of the strut and that the interaction of both
screws may cause functioning problems.
SUMMARY OF THE INVENTION
[0008] One of the objects of the present invention is to provide a
telescopic locking strut which is capable to lock and release, for
instance, heavy aircraft cowls without need of manual
operation.
[0009] It is object of the present invention an electrical
telescopic strut constructions movable between an extended, locked
position and a retracted, unlocked position, comprising: [0010] an
external cylinder having a connection end configured for being
connected to the structure of the aircraft; [0011] an inner
cylinder slidable within the external cylinder and having a second
connection end configured for being connected to a movable
structure, for instance, a door; [0012] a screw rotatable disposed
within the inner cylinder; [0013] a drive attached to the external
cylinder and configured to rotate the screw; [0014] a nut coupled
to the screw and connected to the inner cylinder, said nut being
slidable movable with respect to the external cylinder; [0015] at
least one segment located in a radial opening of the inner cylinder
and movable radially outward and inward in response to the movement
of the nut and configured to engage the external cylinder when
moved radially outward and not to engage the external cylinder when
moved radially inward, the inner cylinder being lockable to the
external cylinder by the segment in an extended position of the
strut, and [0016] a second inner cylinder located external to the
first inner cylinder and internal to the external cylinder when the
first inner cylinder is retracted into the external cylinder, the
second internal cylinder being joined to the first inner cylinder
such that both are displaced together.
[0017] The invention permits to an electromechanical actuator based
on a linear screw the accomplishment of the following additional
advantages: [0018] Extend and retract the telescoping strut under
load to their maximum positions. [0019] Lock and release
automatically without manual operation while the strut under load
is operated by an electromechanical mechanism to avoid accidental
release. [0020] Automatically mechanical lock in extended position.
[0021] Assuring a redundant load path.
[0022] As previously stated, one object of the present invention is
to prevent the inadvertent unlocking of the strut thanks to the
locking mechanism. This mechanism is based on segments and openings
designed for avoiding the unlocking of the strut with the external
load. For unlocking the strut, it is necessary to activate the
electromechanical system to allow the release the strut.
[0023] Still another object is its automatically lock in extended
position and which can only be unlocked by the activation of the
electromechanical system. Without any manual operation to unlock
neither to remove the load from actuator.
[0024] The above objects are accomplished with a feature that
operates the strut to extend and retract under load. For
extending/retracting the strut, the same electromechanical actuator
is used to pull the weight of the cowl and the wind forces by
pulling the inner rod out of the strut with a linear screw.
[0025] Therefore, the strut according to the invention comprises:
an external cylinder, an internal cylinder movable in the external
cylinder in an extending direction and in a retracting direction;
an additional internal cylinder, an elongated screw in the bore of
the external and the internal cylinders and rotatable by a motor
drive; a nut coupled to the inner cylinder and movable in the bore
of the external cylinder in the extending direction and in the
retracting direction responsive to rotation of the elongated screw;
at least a lock segment in the internal cylinder and movable
radially outward and radially inward in response to movement of the
nut. The lock segment engages the external cylinder when moved
radially outward, whereby the internal cylinder is lockable to the
external cylinder by the lock segment.
[0026] The system comprises a double load path, based on a double
internal cylinder and the segments. Therefore, the inner cylinder
is part of the first load path and the second inner cylinder is
part of the second load path. Thus, the system is designed with a
safety requirement categorized as catastrophic, the first level of
safety. There can be no single failure that results in fully
extended actuator retraction.
[0027] The system additionally may comprise double connection ends
to the aircraft structure and to the cowls.
DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 shows a sectional longitudinal plan view of the strut
construction in a retracted, unlocked position according to a
preferred embodiment of the invention.
[0029] FIG. 2 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2.
[0030] FIG. 3 shows a schematic plan view of the load path of an
embodiment of the strut construction in an extended position.
[0031] FIG. 4 shows a schematic plan view of the load path of an
embodiment of the strut construction in an extended position in
case of failure on the segment system.
[0032] FIG. 5 shows a schematic plan view of the load path of an
embodiment of the strut construction in an extended position in
case of failure on the lug of the inner cylinder.
[0033] FIG. 6 shows a schematic plan view of the load path of an
embodiment of the strut construction in an extended position in
case of failure on the lug of the external cylinder.
[0034] FIG. 7 shows a schematic plan view of the load path of an
embodiment of the strut construction in an extended position in
case of failure of the inner cylinder.
[0035] FIG. 8 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 in a retracted position with
compression load.
[0036] FIG. 9 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 in a travelling position with
compression load.
[0037] FIG. 10 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 in a retracted position with traction
load.
[0038] FIG. 11 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 in a travelling position with traction
load.
[0039] FIG. 12 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 showing its position before locking
the segments.
[0040] FIG. 12B shows an enlarged view of FIG. 12.
[0041] FIG. 13 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 showing its position the segments
locked.
[0042] FIG. 13B shows an enlarged view of FIG. 13.
[0043] FIG. 14 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 showing the movement of the nut by the
motor until it clash with the key.
[0044] FIG. 14B shows an enlarged view of FIG. 14.
[0045] FIG. 15 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 showing its position with segments
unlocked.
[0046] FIG. 15B shows an enlarged view of FIG. 15.
[0047] FIG. 16 shows a sectional longitudinal lateral view of the
strut construction of FIG. 2 showing the beginning of the
retraction after locking the segments.
[0048] FIG. 16B shows an enlarged view of FIG. 16.
[0049] FIG. 17 shows a sectional longitudinal lateral enlarged view
of the strut construction of FIG. 2 showing a segment and a
nut.
DETAILED DESCRIPTION OF THE INVENTION
[0050] An embodiment of the present invention for a strut
construction, movable under load from an extended, locked position
to a retracted, unlocked position will be described
hereinafter.
[0051] FIG. 1 shows an embodiment of the collapsible strut
construction in the retracted, unlocked position that comprises:
[0052] an external cylinder (1) having a lug (20) at an end; [0053]
an inner cylinder (2) slidable within the external cylinder (1) and
having a second lug (21) at an end; [0054] a screw (3) rotatable
disposed within the inner cylinder (2); [0055] a drive (4) attached
to the external cylinder (1) and configured to rotate the screw
(3); [0056] a nut (5) coupled to the screw (3) and connected to the
inner cylinder (2), being movable with respect to the external
cylinder (1) responsive to the rotation of the screw (3); [0057] at
least one segment (6) located in a radial opening of the inner
cylinder (2) and movable radially outward and inward in response to
the movement of the nut (5) and configured to engage the external
cylinder (1) when moved radially outward and not to engage the
external cylinder (1) when moved radially inward, the inner
cylinder (2) being lockable to the external cylinder (1) by the
segment (6) in an extended position of the strut, [0058] the strut
further comprises a second inner cylinder (7) located external to
the first inner cylinder (2) and internal to the external cylinder
(1) when the first inner cylinder (2) is retracted into the
external cylinder (1), the second inner cylinder (7) being joined
to the first inner cylinder (2) such that both cylinders (2, 7) are
displaceable together.
[0059] Therefore, both the first (2) and the second (7) inner
cylinder are disposed in the external cylinder (1) and are jointly
movable longitudinally within external cylinder (1). Both the first
(2) and the second (7) internal cylinder are moved outward from the
external cylinder (1) and inward into the external cylinder
(1).
[0060] Typically, the end connection (20) of the external cylinder
(1) of the strut is attached to a fixed aircraft structure and the
end connection (21) of the internal cylinders (2, 7) are attached
to a movable structure, more specifically to a door.
[0061] Extension and retraction of the screw (3) is provided by the
drive (4) arrangement, including a drive motor assembly, a gear
assembly and a brake (36) of the screw (3) which are mounted at the
head end of actuator. Drive (4) assembly includes a housing in
which is disposed a motor. The drive (4) motor is coupled to the
screw (3) located within internal cylinder (1).
[0062] Screw (3) assembly includes an elongated screw (3) and a
compatible nut (5) riding thereon and coupled thereto by thread
engagement, that run in the external helical groove of screw (3),
so that rotation of the screw (3) produces translation of the nut
(5) on the screw (3).
[0063] In the retracted position, both internal cylinders (2, 7)
are disposed inside of the external cylinder (1) with the screw (3)
inside of the internal cylinder (1) and the nut (5) being drawn
substantially to the head end. In this position, actuator is fully
retracted and unlocked.
[0064] Actuator is driven from the retracted position to the
extended position by operating drive (4) motor assembly in a
direction to drive the nut (5) in a direction from head end towards
internal cylinder (2) end. Similarly, actuator is driven from the
extended position to the retracted position by operating electric
drive motor assembly to rotate the screw (3) in an opposite
direction to drive the nut (5) in a direction from rod end towards
head end.
[0065] The external cylinder (1) comprises a locking groove or
opening (24) configured to house the at least one locking segment
(6) in the extended, locked position. Thereat, locking mechanism is
unlocked with the plural segment (6) are in a radially inward
position. Two lock segments (6) are shown in the figures and they
extend radially outward to engage the openings (24) within the
external cylinder (1).
[0066] When actuating power is not applied a lock spring (25)
maintains the nut (5) and therefore the segment (6) in its locked
position.
[0067] In the locked position of locking mechanism, the inner end
of lock segment (6) is adjacent to a cylindrical surface of a
collar (26) located around the nut (5) that is of a given diameter
selected to so position the lock segment (6) a predetermined radial
distance from a central axis of the screw (3) and nut (5). The
collar (26) comprises two cylindrical surfaces of different
external diameter, one leaving the segment (6) in a lower position
and therefore not engaging the recess (24) in the external cylinder
(1) and not locking the strut and a second cylindrical surface
having a larger diameter and locating the segment (6) into the
mentioned recess (24). In the transition between both cylindrical
surfaces a sloped surface exists. The combination of these surfaces
provides a cam for moving lock segments (6) radially inward and
outward for engaging and disengaging lock segments (6) of lock
mechanism. When the nut (5) is moving axially lock segments (6)
move and radially out of the openings (24).
[0068] The position of the collar (26) is additionally secured by
an angle (32) designed into sliding surfaces between segment (6)
and collar (26). This angle (32) is defined in order to guarantee
an irreversible system. Any failure in spring (25) or in a
retaining ring (33) of the piece retaining the spring (25) do not
allow the inadvertent unlocking operation. This angle (32) is used
in both: collar (26) and segment (6) and has to be zero or negative
as depicted in FIG. 17 considering that negative angles are those
measured in the clockwise direction from the positive horizontal
axis.
[0069] The nut (5) has also two outwardly extending flange segments
(27, 29) at each of its opposite ends. One (29) avoids the collar
(26) to step out the nut (5) and the other one (27) retain the
spring (25) extending between the collar (26) and the flange (27).
Lock spring (25) therein serves to bias the nut (5) towards the
locked position, urging the collar (26) to move towards the end of
the screw (3). Flange (29) avoiding the collar (26) to step out the
nut (5), due to the force exerted by the spring (25), is integrated
into the nut (5) avoiding an inadvertent unlocking of the system.
In order to allow the assembly of the spring (25), the other flange
(27) is separated from the nut (5).
[0070] In disengaging the lock mechanism out of the locked
position, the screw (3) is rotated in the opposite direction to
move the nut (5) towards head end. The distal flange (29) of the
nut (5) contacts the collar (26) and urges it (26) towards the
base, therefore the segment (6) is displaced to the lower surface
of the collar (26) and therefore out of the opening (24) of the
external cylinder (1).
[0071] As can be seen in FIG. 3 when the actuator is working
properly the load path (30) goes from the end connection (21)
configured to be coupled to the door, through the inner cylinder
(2) until the segment (6) in which the load is transferred to the
external cylinder (1) and then to the end connection (20)
configured to be coupled to the aircraft structure. In the extended
and locked position, a substantial portion of the internal
cylinders (2, 7) extend beyond the end of the external cylinder
(1).
[0072] The locking mechanism locks the internal cylinders (2, 7) in
its extended position relative to the external cylinder (1) so that
the structural loads are entirely supported by the external (1) and
internal cylinder (2) which are structurally locked together by
locking mechanism as can be seen in FIG. 3.
[0073] In the extended position, the nut (5) is driven into an
over-travel position wherein locking mechanism locks the first
internal cylinder (2) to external cylinder (1) with the lock
segment (6) of locking mechanism having been driven radially
outward to engage into an opening (24) in the wall of the external
cylinder (1).
[0074] The strut comprises a mechanical element extending between
the first inner cylinder (2) and the second inner cylinder (7)
configured to avoid the axial and radial relative movement between
both cylinders (2, 7). Said mechanical element is a pin (10)
located in an opening of the first inner cylinder (2) and in an
opening of the second inner cylinder (7). As additionally, the
second inner cylinder (7) is in axial contact with the first inner
cylinder (2), a second load path is achieved. Said axial contact is
performed by two corresponding flanges (34, 35) at the end
proximate to the segment (6) orifice of the inner cylinder (2).
[0075] FIG. 7 discloses the actuator working under condition of
failure of the inner cylinder (2). In this particular case the load
will be transferred from the lug (21) of the inner cylinder (2) to
the second inner cylinder (7) by the pin (10) and due to the axial
contact between them (2, 7) to the segment (6) and to the external
cylinder (1).
[0076] The electrical telescopic strut construction shown in the
figures comprises a mechanical element extending between the inner
cylinder (2) and the nut (5) configured to avoid the radial
relative movement between both elements (2, 7). The mechanical
element is a pin (11) located in an opening of the inner cylinder
(2) and in an opening of the nut (5) thus restricting the relative
radial movement between the nut (5) and the inner cylinder (2). The
pin (11) or pins (11) are located in an extension (31) of the nut
(5). The opening of the nut (5) is an axial opening (12) such that
there is an axial relative movement between the inner cylinder (2)
and the nut (5). Said mechanical element allows a second load path
as depicted in FIG. 4 in case of failure of the segment (6) being
the load transferred from the internal cylinder (2) to the nut (5)
and from there to the screw (3). Therefore, the segments (6) with
automatic locking are part of the main road and the screw (3) with
brake (36) is part of the second loading path as in case of failure
of the segments (6) the assembly screw (3)-brake (36) can stand the
applied loads in a second load path.
[0077] The nut (5) is connected mechanically to cylinder (2) by
means the radial pin (11) located in slidable axial gaps (12). The
axial gap (12) allows the strut the absorption of traction and
compression loads by displacing the the nut (5) with respect to the
internal cylinder (2) the length of the axial gap (12). From fully
extended or retracted position, the first linear movement of nut
(5) created by the rotational movement of screw (3), will absorb
this axial gap (12) before any linear movement of cylinders (2, 7).
This free movement of the nut (5) with respect to the cylinder (2)
allows the unlocking of collar (26) and segments (6) by the
displacement of the nut (5) towards the collar (26) until the nut
(5) reaches said collar (26) and pushes it to achieve the unlocking
of the system as can be seen in FIGS. 13 to 15.
[0078] During normal operation to extend and retract the strut, in
which the segment (6) is not locked, the load path (30) is
conducted through the main mechanical parts as screw (3), pins (11)
and cylinder (2). Therefore, the external dynamic loads are not
applied through segment (6) during extension and retraction
allowing a simpler sizing of segment (6), reducing the shear area
required. Segment (6) only supports the static external load in
fully extended and locked position.
[0079] FIG. 4 shows a case in which there is a failure in the
segment (6), in that case, and due to a double path of the
actuator, the load is transferred from the inner cylinder (2) to
the nut (5) thorough pin (11) and afterwards to the screw (3). The
screw (3) is locked by the brake (36) and therefore the load is
transferred to the brake (36) and to the end connection (20).
[0080] The second inner cylinder (7) comprises a second lug (22) at
its free end. Additionally, the second inner cylinder (7) is in
axial contact with the first inner cylinder (2), the second lug
(22) and the axial contact defining an additional load path as
depicted in FIG. 5.
[0081] FIG. 5 discloses the actuator working under condition of
failure of the end connection (21) coupled to the inner cylinder
(2). In this particular case the load will be transferred from the
end connection (22) coupled with the second internal cylinder (7)
to the segment (6) and from there to the external cylinder (1).
[0082] The embodiment also shows a second end connection (23)
configured to be connected to the aircraft structure and coupled to
the armature which is in turn coupled to the external cylinder (1)
by an axial contact.
[0083] FIG. 6 discloses the actuator working under condition of
failure of the end connection (20) coupled to the external cylinder
(1). In this particular case the load will be transferred from the
external cylinder (1) to the second end connection (23) of the
external cylinder (1).
* * * * *